You could order at Gold Phoenix PCB - the size of the design is just below their maximum allowable single board size for their “specialprice” prototype order. The 155 sq inch panel gives you three boards - sometimes they will actually make it four, but they don’t promise that so don’t expect it.
All my protoboards are gone, sorry. If I was located in a place where shipping costs are reasonable then I’d probably do another run. However, boards that size are expensive to ship from here, and if you wanted tracking it’s even worse. If you stay within single-digit quantities you will probably not find a better offer than what I pointed you towards.
I have just ordered one from Goldphoenixpcb.com and they charged 103 USD (incl. shipping within the US). I guess there are other alternatives in Europe…